The concept of orienting strands by passing the strands through narrow vertical passages (compared with the axial length of the strands to be oriented) is practised in the wafer board or strand board industry and has been for some time.
One such device is shown in U.S. Pat. No. 3,115,431 issued Dec. 24, 1963, to Stokes et al. This device includes the plurality of intermeshed rotating disks mounted on a plurality of substantially parallel side-by-side shafts positioned-in a plane. The disks on the shafts are uniformly positioned intermediate disks on their adjacent shafts. In the arrangement described, the disks on adjacent shafts turn in the same direction, except for the last disks in the sequence which turn in the opposite direction. This type of arrangement (hereinbelow referred to as the Stoke's arrangement) has been found satisfactory particularly for use with long strands. The disclosure of the Stokes et al. patent is incorporated herein by reference.
Another similar device is shown in the Burkner U.S. Pat. No. 4,666,029 issued May 19, 1987 but wherein the disks on adjacent shafts are arranged in pairs in side by side relationship with the disks forming one of the pairs defining one side of an orienting passage and the disks forming the next axially space pair defining the other side of the passage. This arrangement (hereinafter referred to as Burkner's arrangement) is also satisfactory but the Stokes' arrangement is less complicated and appears to be about as effective in aligning the strands as the Burkner arrangement. The Burkner et al. patent is incorporated herein by reference.
Both of these devices use their rotating disks to carry the longer length strands that did not pass directly between the axially spaced disks along the top of the disks toward one end where the axial spacing between the disks is wider so that the long strands are preferentially positioned towards one end of the orienter and the short strands at the other.
In a modified version of the arrangements as described in Crittenden et al.'s U.S. Pat. No. 5,325,954 issued Jul. 5, 1994, at least a pair of decks, i.e. preorienter and orienter are used. This significantly improved the operation of the system and better ensures that the strands, in particular, long strands over about 6 inches pass through the vertical passages in the bottom orienting deck more easily by first tipping the strands via the disks in the preorienter and directing them more effectively into the relatively narrow passages in the orienter. This system provides a significant improvement over both the Burkner and Stokes arrangements and is particularly suited for handling long strands.
The orienting system of U.S. Pat. No. 5,325,954 generally employs a relatively long bottom deck with wider axial disk spacing toward one end of the orienter, but does not segregate the strands by length to the extent that occurs with the Burkner and Stokes arrangements.
It is known that the height of the lower edge of the bottom orienting deck above the mat or lay-up formed on the collecting belt has a significant influence on the retained orientation of the wafers or strands on the belt. The larger this space the greater the loss of orientation of the strands as attained in the orienter, thus it is preferred to keep this distance relatively small in the order of between 1 and 3 inches, preferably smaller to minimize this loss of orientation.
It will be apparent, if there is segregation of the strands by length, the strands are laid on the collecting belt over a longer length of the belt. This is not in itself a problem, however, if the distribution of strands along the length of the orienter is not uniform, the height of the mat above the belt will build at a nonuniform rate so that the height of the mat above the belt will form a hump towards one end of the orienter.
This means that the sloped bottom deck of the orienter must be adjusted to accommodate the hump so that the spacing between the bottom deck and the top of the strands on the belt may be set at the desired distance at the top of the hump but anywhere off the hump, so that the average angle of orientation of strands in this part of the orienter is significantly increased, i.e. orientation is lost.
U.S. Pat. No. 3,807,931 issued Apr. 30, 1974 to Wood et al. describes another form of orienter which uses a number of vertically stacked decks each formed by stationary vertical fins each provided with a vibrating cap that improve movement of the wood particle there between. Each deck has a number of fins that is a multiple of the number of fins in the deck immediately above it so that the fins on the upper deck directly overlie corresponding fins on the lower deck and the flow of strands is divided by the upper deck and the divisions so formed further subdivide by the next lower deck. In this device, the spacing between the fins on the top deck is about half the average length the strands that are to be oriented and the spacing between the upper and lower deck is defined as the distance greater than the average length of the strands. The orienting system of this patent clearly would not be effective for long wafers nor would it function well for conventional length (3 to 4 inch) strands.
Canadian patent 920,529 issued Feb. 6, 1973 to Turner et al. shows yet another form of orienter wherein partition walls are designed to move to prevent plugging.